城市轨道交通槽型梁和箱梁低频声学性能比较与机理分析

城市轨道交通槽型梁和箱梁低频声学性能比较与机理分析Title:ComparisonandMechanismAnalysisofLow-FrequencyAcousticPerformancebetweenTrough-ShapedandBoxGirderinUrbanRailTransitIntroduction:Withtherapiddevelopmentofurbanrailtransitsystems,theacousticperformanceoftrackstructureshasbecomeanimportantconsiderationforimprovingpassengerexperienceandreducingnoisepollution.Twocommonlyusedtrackstructuresarethetrough-shapedbeamandtheboxgirder.Thispaperaimstocompareandanalyzethelow-frequencyacousticperformanceofthesetwostructuresandexploretheunderlyingmechanisms.ComparisonofLow-FrequencyAcousticPerformance:1.NoiseGeneration:a)Trough-ShapedBeam:Thedesignofthetrough-shapedbeamincludesarailembeddedinaconcretetrough.Asthetrainpassesoverthebeam,thewheelsgeneratenoiseduetovibrationsandirregularitiesontherailsurface.Thenoisegeneratedisprimarilycausedbycontactbetweenthewheelsandthetrack.b)BoxGirder:Inthecaseofaboxgirder,therailisplacedontopofthestructureratherthanbeingembedded.Thenoisegeneratedinthiscaseismainlyduetovibrationsoftherailcausedbythemovingtrain.2.NoisePropagation:a)Trough-ShapedBeam:Duetoitssolidconcretestructure,thetrough-shapedbeamactsasabarriertothepropagationofnoise.Thehighmassandthicknessofthebeameffectivelyblockthetransmissionofnoisegeneratedbythewheels.b)BoxGirder:Theopenstructureoftheboxgirderallowsforgreaternoisepropagation.Soundwavesgeneratedbythemovingtraincanfreelypropagatethroughtheairandreachthesurroundingenvironment.3.NoiseReductionMeasures:a)Trough-ShapedBeam:Tofurtherreducenoise,additionalmeasurescanbeimplementedalongthetrough-shapedbeam.Forexample,vibrationisolationmaterialscanbeappliedtotheinteriorsurfaceofthetrough.Thesematerialshelpabsorbvibrationsandreducenoisetransmission.b)BoxGirder:Inthecaseofaboxgirder,noisereductionprimarilyfocusesonreducingvibrations.Dampingmaterialscanbeappliedtothesurfaceoftheboxgirdertoabsorbvibrationsandreducenoisegeneration.MechanismAnalysis:1.NoiseReflectionandAbsorption:a)Trough-ShapedBeam:Thesolidconcretestructureofthetrough-shapedbeamreflectsasignificantportionofthenoisegeneratedbythewheels.Someofthenoiseisalsoabsorbedbythebeamitselfduetoitsmassanddensity.b)BoxGirder:Theopenstructureoftheboxgirderallowsforminimalreflectionofnoise,resultinginahigherpropagationofsoundwaves.However,theapplicationofdampingmaterialsonthesurfaceofthegirderhelpsabsorbacertainamountofnoiseenergy.2.NoiseTransmission:a)Trough-ShapedBeam:Thethickandmassivestructureofthetrough-shapedbeamimpedesnoisetransmissionthroughthematerial.Thehighdensityoftheconcreteanditsinternaldampingpropertiesalsocontributetoreducingnoisetransmission.b)BoxGirder:Theopenstructureoftheboxgirderallowsnoisetotravelmorefreelythroughtheair,resultinginahigherlevelofnoisetransmission.Conclusion:Inconclusion,thetrough-shapedbeamandboxgirderhavedistinctdifferencesinlow-frequencyacousticperformanceinurbanrailtransitsystems.Thetrough-shapedbeamactsasabarriertonoisepropagation,withfewervibrationsgeneratedbythewheelsreachingthesurroundingenvironment.Theboxgirder,ontheotherhand,allowsforhighernoisepropagationduetoitsopenstructure.However,noisereductionmeasurescanbeemployedforbothstructurestooptimizetheiracousticper